Overview

- Glaciers of Ayas Valley (Breithorns - Castore) -

The "welding" between the Valleys of Ayas and Gressoney or Lys occurs, as well as through the hills sites on the watershed dividing the two, for the glaciers in the upper part of the same, merge into a single casting. After the Breithorns Glacier that tied the Valtournanche at the Ayas Valley and then that of the Torrent Marmore with Evançon, a series of glaciers, fan out into the valley accompanying the crest of Swiss-Italian border. First, to the Southwest with the Glaciers Aventine, practically a continuation of that of the Breithorns from which it is separated from the bulk Gobba (Hump) of Rollin (3.899m), and the two glacial "tongues" ​​of the Grand and Petit Verra or Veraz, then from Glacier Castor, inserted between this summit and his shoulder Eastern or Punta Felik. Farther South is the direction and includes those Felik or Martelli, Perazzi and the much larger Western Lys, at the foot of the cirque between the two Lyskamms, Western and Eastern, but these is now leaning towards the Gressoney Valley.
Then the long divider between the valleys of Ayas and Gressoney stretches Southward completely free of ice up above the Communes of Donnas and Pont Saint Martin, in the Central Valley of the River Dora Baltea. In the watershed between the Superior Bettolinaz Hill, the Testa Grigia (Gray Head; 3.313m) and the Ranzola Pass are only a series of lakes (among which we highlight those Pinter and Palasina) which suggest what would be the ancient expansion of the ice. Some signs of the snows are still at the Northern base of Mount Nery or Becca of Frudiera, but now it's snowfields overlying the two beautiful lakes and homonyms, witnesses of the withdrawal of the same. Still some small glacial firn in the Walloon Chasten in the amphitheater at the base of Mount Voghel and the two Dames de Challand. But no shadow of glaciers and lakes even more signals, demonstrating that in this area the retreat of the ice was even more precocious.
Analogously, back, on the spur partition with the Valtournenche Valley: from Gran Sometta and down until the Mount Zerbion ed alla Testa di Comagna above Chatillon and Saint Vincent Municipalities, we will not find more glaciers, while further inland, a more small, said Tzère, fastens, as an appendix, to the Aventine and its waters flow into the underlying Grand Lac, in a small basin enclosed amongst the Bivouac City of Mariano and the Rocca or Mont of Verra(z).